• Nuclear Engineering and Technology
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• 제56권3호
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• pp.949-958
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• 2024

In contrast to all-time flooded small modular reactor (SMR) systems, an in-kind flooding safety system (FSS) has been proposed as a passive safety system applicable to small modular reactors (SMRs) that adopt a metal containment vessel (MCV). Under transient conditions, the FSS can provide emergency cooling to dry reactor cavities and sustain long-term coolability using re-acquired evaporated steam in the reactor building on demand. When designing an FSS, the effect of the flooding flow area is vital as it affects the overall accident sequence and safety. Therefore, in this study, a MELCOR model of a reference SMR is developed and numerical analysis is performed under postulated accident scenarios. Without flooding, the MCV pressure of the reactor module exceeds the design pressure before core damage. To prevent core damage, an emergency flooding strategy is devised using various flow path parameters and requirements to ensure an adequate emergency coolant supply before the core damage is investigated. The results indicate that a flow area exceeding 0.02 m2 is required in the FSS to prevent MCV overpressure and core damage. This study is the first to report a strategic analysis for appropriately sizing an FSS flooding valve applicable to innovative SMRs.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1209-1212
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• 2007

Urban flooding with surcharges in sewer system was investigated because of unexpected torrential storm events these days, causing significant amounts of human and economic damages. Although there are limitations in forecasting and preventing natural disasters, integrated urban flooding management system using the SWMM(Storm Water Management Model) engine and Web technology will be an effective tool in securing safety in operating rubber-tired transportation system. In this study, the study area, located in Chuncheon, Kangwon province, was selected to evaluate the applicability of the SWMM model in forecasting urban flooding due to surcharges in sewer system The catchment are 21.10 ha in size and the average slope is 2% in lower flat areas. Information of subcatchment, conjunctions, and conduits was used as the SWMM interface to model surface runoff generation, water distribution through the sewer system and amount of water overflow. Through this study, the applicability of the SWMM for urban flooding forecasting was investigated and probability distribution of storm events module was developed to facilitate urban flooding prediction with forecasted rainfall amounts. In addition, this result can be used to the establishment of disaster management system for rainfall safety of rubber-tired tram in the future.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.61-65
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• 2008

Urban flooding with surcharges in sewer system was investigated because of unexpected torrential storm events these days, causing significant amounts of human and economic damages. Although there are limitations in forecasting and preventing natural disasters, integrated urban flooding management system using the SWMM engine and Web technology will be an effective tool in securing safety in operating Bi-modal transportation system. In addition, the integrated urban flooding management system can be linked with general and transportation-related disaster management system in the future. In this study, With simulated values by the SWMM, which is a core engine of the Bi-modal disaster management system, flash flooding area estimation module was developed. Thus, the SWMM system codes were modified and new module was developed and integrated with the existing SWMM interface using the Delphi programming language. The flash flooding area estimation module is fully integrated with the SWMM interface, thus the area is estimated on-the-fly inside the system.

• Safety and Health at Work
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• 제9권4호
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• pp.381-387
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• 2018

Background: Physician behaviors that undermine a culture of safety have gained increasing attention as health-care organizations strive to create a culture of safety and reduce medical errors. We developed, implemented, and assessed a course to teach physicians skills regarding effective coping and interpersonal communication skills and present our results regarding outcomes. Methods: We examined a professional development program specifically designed to address unprofessional or distressed behaviors of physicians, and we evaluated the impact on burnout, quality of life, and emotional flooding scores of the physicians. Assessments of burnout, quality of life, and emotional flooding were assessed preintervention and postintervention. Results: Results demonstrated statistically significant reductions over time in physicians' emotional flooding and emotional exhaustion (EE). Specifically, using a Wilcoxon Signed-Rank test, results revealed that flooding scores at follow-up were statistically significantly lower than at baseline, V = 590, p < 0.05, and EE and personal accomplishment distributions were found to significantly deviate from normal as indicated by Shapiroe-Wilks tests (p < 0.05). A Wilcoxon signed-rank test indicated that EE scores were significantly higher at baseline compared to follow-up 1, V = 285, p < 0.05. Conclusion: We conclude that the physician participants who enrolled in the educational skills training program improved scores on emotional flooding and EE and that this may be indicative of improved skills related to their experiences and learning in the program. These improved skills in physicians may have a positive impact on the overall culture of safety in the health system setting.

• 전기학회논문지P
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• 제58권1호
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• pp.90-94
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• 2009

The inundation of substation and ground power equipment breaks out every summer season in low-lying downtown and low-lying shore by localized heavy rain, typhoon and tidal wave. For diminishing flood damage of electrical equipment in the root, flood protection system which is used the basic frame of Pad transformer is developed using pneumatic pressure. This system is established on pressure generator equipment and sensor of flooded level operates at flooding occurrence and is maintained a shutting tightly structure. The system is able to protect indraft water in Pad Transformer and supply the electricity at emergency(flooding). And we tested safety for insulation resistance at flooding and applying an electrical current. We estimate that loss cost which is caused by with flooding and the power failure will be diminished if it is addition to advances the reliability evaluation by setting an example.

• 조명전기설비학회논문지
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• 제28권12호
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• pp.38-44
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• 2014

The photovoltaic power system is performing power generation by being installed in outdoors. Therefore it has the characteristics affected by environmental factors. In particular, if the solar power generation facility connected to the grid, the power can be generated continuously in a state of being secured operating voltage of the inverter and solar irradiation. In that case, if an abnormal situation such as flooding or heavy rains has occur, the possibility of electric shock or damage of facilities due to current leakage or a floating matters is present. In this paper, we performed electrical safety assessment about the connection part, junction box and cable of the solar module when the solar power system was flooded. we also assessed whether or not the leakage current is occurred in case of the cable was damaged. As a result, in case of the leakage current is large, we can be known that it is the risk of electric shock as well as cause of inverter damage.

• Nuclear Engineering and Technology
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• 제56권7호
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• pp.2534-2544
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• 2024

This paper proposes a flooding safety system (FSS) and its operation strategy that can provide long-term safety and effective maintenance for modules of small modular reactor (SMR) and metal containment maintained at dried environment during normal operation. During hypothesized accidents, the FSS re-collects the evaporated steam into the common pool by the condenser installed above the common water pool and provides an emergency coolant for the cavities and auxiliary pools. This study suggested that the condensate re-collection strategy using the FSS can effectively delay the depletion of available water in response to the accidents. Without recollection, the achievable grace periods ranged from 44 to 1507 days for six-module and one-module accidents, respectively. However, with a full re-collection (ratio = 1.0), the time to total depletion of emergency coolant was estimated indefinite. Even with a partial re-collection ratio of 0.3, a grace period of 83.5 days could be ensured for a six-module transient. This study reported the effectiveness of condensate re-collection and the FSS as an innovative safety management strategy and system. Employing a condensate re-collection strategy with a high re-collection ratio can enhance the long-term safety and effective convenience of SMR operations and maintenance.

• 한국안전학회지
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• 제35권2호
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• pp.100-110
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• 2020

Recently, the frequency of typhoon and torrential rain due to climate change is increasing. In addition, the upsurge in the complexity of urban sewer network and impervious surfaces area aggravates the inland flooding damage. In response to these worsening situations, the central and local governments are conducting R&D tasks related to predict and mitigate the flood risk. Researches on the analysis of inundation in urban areas have been implemented through various ways, and the common features were to evaluate the accuracy and justification of the model by comparing the model results with the actual inundation data. However, the evaluation procesure using available urban flooding data are not consistent, and if there are no quantitative urban inundation data, verification has to be performed by using press releases, public complaints, or photos of inundation occurring through 'CCTV'. Because theses materials are not quantitative, there is a problem of low reliability. Therefore, this study intends to develop a comparative analysis procedure on the quantitative degree and applicability of the verifiable inundation data, and a systematic framework for the performance assessment of urban flood analysis model was proposed. This would contribute to the standardization of the evaluation and verification procedure for urban flooding modelling.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2018년도 추계학술대회
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• pp.241-247
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• 2018

Deep-sea fishing vessel No. 501 Oryong was fully flooded through its openings and sunk to the bottom of the sea due to the very rough sea weather on the way of evasion after a fishing operation in the Bearing Sea. As a result, many crew members died and/or were missing. In this study, a full-scale ship flooding and sinking simulation was conducted, and the sinking process was analyzed for the precise and scientific investigation of the sinking accident using a highly advanced Modeling & Simulation (M&S) system of the Fluid-Structure Interaction (FSI) analysis technique. To objectively secure the weather and sea states during the sinking accident in the Bering Sea, time-based wind and wave simulation at the region of the sinking accident was conducted and analyzed, and the weather and sea states were realized by simulating the irregular strong wave and wind spectrums. Simulation scenarios were developed and full-scale ship and fluid (air & seawater) modeling was performed for the flooding sinking simulation, by investigating the hull form, structural arrangement & weight distribution, and exterior inflow openings and interior flooding paths through its drawings, and by estimating the main tank capacities and their loading status. It was confirmed that the flooding and sinking accident was slightly different from a general capsize and sinking accident according to the simple loss of stability.

• Nuclear Engineering and Technology
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• 제56권3호
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• pp.1022-1028
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• 2024

A neutronics study of a supercritical CO₂-cooled fast reactor core for nuclear propulsion has been performed in this work. The thermal power of the reactor core is 30 MWth and a ceramic UO₂ fuel can be used to achieve a 20-year lifetime without refueling. In order to make a compact core with inherent safety features, the drum-type reactivity control system and folding-type shutdown system are adopted. In addition, we suggest a cold shutdown system using gadolinium as a spectral shift absorber (SSA) against flooding. Although there is a penalty of U-235 enrichment for the core embedded with the cold shutdown system, it effectively mitigates the increment of reactivity at the flooding of seawater. In this study, the neutronics analyses have been performed by using the continuous energy Monte Carlo Serpent 2 code with the evaluated nuclear data file ENDF/B-VII.1 Library. The supercritical CO₂-cooled fast reactor core is characterized in view of important safety parameters such as the reactivity worth of reactivity control systems, fuel temperature coefficient (FTC), coolant temperature coefficient (CTC), and coolant temperature-density coefficient (CTDC). We can say that the suggested core has inherent safety features and enough flexibility for load-following operation.